Process of preparing nitrogencontaining compounds



is that known as digester tankage.

Patented June 27, 1939 PATENT oeelns PROCESS OF PREPARING NITROGEN- CONTAINING COMPOUNDS Anderson W. Ralston and William M. Selby, Chicago, Ill., assignors to Armour and Company, Chicago, 111., a corporation of Illinois No Drawing.

Application February 26, 1936,

Serial No. 65,923

5 Claims.

This invention relates to processes of preparing nitrogen-containing compounds and it comprises processes wherein a mixture of waste protein materials and low grade fatty materials are destructively distilled.

Vast quantities of nitrogen-containing waste materials are available as by-products in the meat packing industries. These materials are largely of a protein nature. One abundant source Another is fish meal, and a third is waste scraps of hide materials such as scrap leather, skins, hair, and the like. These protein-containing products are of relatively little value at the present time. Fre- J5 quently they are used in fertilizers for their nitrogen content but the nitrogen is not in a particularly desirable form. As stated, huge quantities of Various waste protein mixtures are available; the problem is to find commercial uses 20 for them.

Similarly, vast quantities of low-grade fats and fatty acids are obtained as by-products in the packing industry. Such fatty acids and fats are the crude black fatty acids obtained in the 25 refining of cottonseed and other vegetable oils, so-called garbage grease fatty acids; and there are many other kinds of crude materials of relatively slight value unless put through expensive refining operations.

30 We have set ourselves to the problem of developing uses for such materials and we have discovered that mixtures of waste protein-containing products and fats or fatty acids, when destructively distilled, will yield distillates con- 35 taining nitrogen compounds of value in the arts.

For example, we have been able to obtain distillates containing various nitriles such as valeronitrile, palmitonitrile, and stearonitrile. These distillates also contain pyridine-like compounds. We have found pyridine, quinoline and also aliphatic amines in our products. In many instances the distillates we obtain need not be separated into their constituents. The distillates are useful as such in a number of industrial 45 relations. For example, we can use them in insecticidal compositions, as solvents, and as raw materials for the preparation of other organic compounds. Thus we can subject distillates containing large quantities of aliphatic nitriles to 50 reduction with hydrogen, this giving us primary and secondary amines.

Although our invention is primarily useful in the preparation of useful products from crude or waste fats and fatty acids and proteins, we

5 need not always use low grade fats and fatty oils.

We can, for example, destructively distil a mixture of crude protein-containing substances with ordinary cottonseed oil, palm oil, lard, lard fatty acids, and similar relatively high grade fats. However, our process is of greater economic sig- 5 nificance in the treatment of the low grade fats.

In many respects, the products which we obtain as a result of the destructive distillation of a mixture of proteins and fats are similar to bone oil. This oil is a product resulting from the destructive distillation of bones and it contains valuable organic nitrogen compounds. However, it is surprising that a mixture of crude proteins and fats can be made to yield valuable organic nitrogen compounds on distillation because we would ordinarily expect that the proteins and the fats would simply decompose independently to give products such as tars which would have no value.

We shall now describe our invention with speg0 cial reference to the destructive distillation of mixtures of digester tankage and fats. Digester tankage is the designation given dried waste protein materials such as crude mixtures of dried blood, bits of skin and other carcass residues. 5

100 parts of digester tankage and 100 parts of fish oil are mixed together and enough sand or other inert solid material added to make a thick paste. This inert material is simply used to assist in the destructive distillation of reacting materials. The mixture is then placed in a distillation apparatus of conventional type. Advantageously this consists of an ordinary externally heated still or retort connected to a water cooled reflux condenser which is in turn connected to condensers for condensing products passing through the reflux. The purpose of the reflux condenser is to return to the still any fats or oils which might tend to distill out without decomposition. During distillation some water distills, escapes through the reflux condenser, and is condensed. As the temperature in the still rises, we find that at 100 C. considerable quantities of water distill over and at 250 C. an oily condensate, which is immiscible with water, is obtained. We continue the distillation until the temperature in the still reaches about 350 C. The actual time required for the destructive distillation will, of course, depend upon the quantity of materials distilled and the size of the distilling apparatus.

The oily condensate referred to above is a bluish-black ammoniacal smelling oil. It has an initial boiling point of 96 C. and a final boiling point of 275 C. More than half of it is a light colored oil with a pyridine like odor containing about 2.4 percent of combined nitrogen. This fraction of the product is that which remains after extracting the initial oily distillate with hydrochloric acid and with potassium hydroxide solution to remove acidic and basic constituents.

In another example we distill a mixture of 100 parts of fish oil and 100 parts of digester tankage as in the example just described. We obtain an oily condensate which we extract with percent of hydrochloric acid solution and with 10 percent of potassium hydroxide solution to remove acidic and basic constituents and finally extract the oily residue with ether. The ether extract, after removal of ether, amounts to 64 parts by weight and contains a mixture of pyridine, quinolines, nitriles, and other organic nitrogen compounds.

In another example we start with 50 parts of crude digester tankage admixed with 50 parts of low grade fatty acids such as cottonseed foots. This mixture is destructively distilled up to a temperature of about 350 C. We obtain 73 parts of an oil much like that obtained in the previous examples. On fractional distillation this oil gives the following fractions.

Fraction 1-100-200 C.6 parts.

Fraction 2200-250 C.-14 parts.

Fraction 3-250-300 C.- parts.

Fraction 4-300-325 C.--33 parts. Kjeldahl analysis showed the following percentages of nitrogen in these fractions.

Fraction 11.3

Fraction 21.2

Fraction 3--1.6

Fraction 4--2.8

Most probably fraction 1 is composed of low molecular weight aliphatic nitriles and possibly some hydrocarbons. Fraction number 4 probably contains a preponderance of cyclic nitrogen compounds.

Because of the complex nature of the products which are obtained in the destructive distillation of these mixtures we cannot state definitely what compounds are actually formed. Possibly some considerable quantities of hydrocarbons are present in the final products. Rather large quantities of gas are, as would be expected, one of the decomposition products. Most all of the mixture of starting materials is converted to water, oily condensate, and gas. This gas contains much ammonia and low-boiling hydrocarbons, possibly ethane and methane.

In the destructive distillation We find it best to avoid the presence of any oxygen or air in the distillation system. Air materially increases the decomposition of the fats to products of little value. Moreover, much air, creates an explosion hazard.

In most instances we operate at ordinary atmospheric pressure but we can increase the pressure with advantage. For example, we can operate at pressures as high as 50 or, 100 pounds, or even higher, and obtain beneficial results. The chief advantage of pressure, however, is simply that of permitting us to operate at somewhat higher heating temperatures in the still. By means of pressure we can maintain the reactants in liquid phase during the destructive distillation and thus prevent, to a large degree, much of the normal evaporation or distillation of the fats or fatty acids.

We most always prefer to operate under moderately elevated pressures when the vapor pressure of the reactants is considerable at a temperature of 100 to 200 C. As stated, pressure enables us to keep the volatile reactants in the distillation zone. Thus, under pressures of 50 pounds per square inch or higher we can run the temperature up as high as 500 C. during the pyrolytic treatment.

For reasons not clearly understood we find that superior results are obtained when the quantities of fat or fatty acid and protein waste are about equal. But We are not to be limited to any specific proportions. We have operated satisfactorily with ratios of 1 part of fatty material to 5 parts of protein material and with ratios of 1 part protein to 5 parts fatty material. Availability of crude materials for distillation will determine the relative proportions of fat and protein to some extent but we ordinarily prefer to have at least as much crude protein as fat present.

Our invention is therefore to be distinguished from processes of destructively distilling protein materials per se. We know it to be old to pyrolyze proteins and that such pyrolysis will yield nitrogen-containing organic compounds such as ring compounds related to quinoline. But these processes do not yield things like nitriles; neither does the simple pyrolysis of proteins alone yield oils similar to bone oil. But when a fatty material is added to the proteins and the mixture pyrolyzed the character of the products indicates that profound reactions between protein or its decomposition products and fat or its decomposition products has occurred. The nature of these reactions is obscure and we do not attempt to account for them.

Having thus described our invention what we claim is:

1. The process of preparing nitrile-containing mixtures of nitrogenous organic compounds which comprises preparing a mixture of waste proteincontaining materials in the nature of digester tankage, waste material from the meat packing industry, scrap leather, fish meal, skins and hair and fatty materials of the class consisting of fats and fatty acids of the type found in naturally occurring fats and fatty oils as glycerides, heating the mixture in the substantial absence of air to a temperature within the range of about 250 C. to about 350 C. to cause the protein material and fatty material to react and condensing a water immiscible oily condensate distilled from the mixture during the heating.

2. The process as in claim 1 wherein the amounts of waste protein-containing materials and fatty materials are approximately equal.

3. The process as in claim 1 wherein the fatty material is fish oil.

4. The process as in claim 1 wherein the protein material is digester tankage and the fatty material is fish oil.

5. The process of preparing nitrile-containing mixtures of nitrogenous organic compounds which comprises admixing about equal parts of digester tankage and fish oil, heating the mixture in the substantial absence of air at a temperature within the range of about 250 C. to about 350 C, and condensing an oily condensate distilled from said mixture during the heating.

ANDERSON W. RALSTON. WILLIAM M. SELBY. 

